It has been known to construct laser tubes as a continuous thick wall tube having a central discharge bore and gas return bores spaced radially outward from the discharge bore. A laser tube has also been constructed from relatively thick wall segments with mating faces and aligned bores providing discharge and gas return bores. U.S. Pat. Nos. 3,501,714 and 3,670,262 illustrate two forms of the segment-type construction.
It has also been known to provide a continuous tube with a series of refractory metal, relatively thin discs centrally mounted on longitudinally-spaced annular metal supports. The main discharge bore is defined by holes in the center of the refractory metal discs and the gas return paths are defined by holes in the annular metal supports. U.S. Pat. No. 4,376,328 illustrates the described refractory metal disc construction and also illustrates coaxially aligned cylindrical shields on the annular metal supports to control gas pumping within the tube.
In U.S. Pat. No. 4,553,241 applicant disclosed a still further improved segment-type laser tube construction formed by metallic cup members mounting relatively thin discs made of refractory metal with each cup member being supported within a relatively thin cylindrical segment formed of electrically insulating material. Structure adapted to either liquid or air cooling is illustrated. U.S. Pat. No. 4,553,241 sets forth several advantages achieved by the improved segmented laser tube construction described in the patent and among which was the advantage of having an economical manufacturing cost. With continued experience and increasing price competition, it has become evident that even further improvements are needed. In particular, there is a need to further reduce the cost of manufacturing a segmented-type laser tube, a need to increase the efficiency of the segmented-type tube so as to have the advantage of the efficiency of the normally more efficient solid bore tube, a need to provide a segmented-type construction which is easy to start and a need to provide a gas return system which resists bypass discharge and with acceptable dissipation of heat from the discharge bore to the surrounding cooling medium, whether water or air.
Taking all the known prior art into account, it has not heretofore been known in a segment-type laser tube to form the laser discharge in a series of axially-aligned ferrules, one per segment, of a length substantially equal to the width of the segment and support the ferrules with heat conductive structure mounted within the individual segment in which the ferrule is mounted and form a tortuous gas return path in such supporting structure. The result of such arrangement is to achieve substantially the efficiency of a solid bore tube.
With the foregoing background and practical considerations in mind, the present invention is directed to providing a further significantly improved, segmented, ceramic-metal laser tube construction. While primarily intended for use is water-jacketed argon-ion lasers, the improved tube construction in also anticipated to find application in those types of laser tubes having fin-type air cooling. The achieving of these improvements and other objects will thus become apparent as the description proceeds.